Lie to prevent an obstacle

I'm abroad with a traditional friend, minus the fact that abroad he eats chicken/meat in restaurants that are of course not kosher (I don't eat pork or anything like that). Today he wanted to eat somewhere, so I went to check how much it costs and told him another, more expensive price so he wouldn't buy it because it's not kosher and he really didn't buy it. Is it my duty to lie to him like that? At least am I allowed to? If it's forbidden to lie to him, then after I lied to him and it's over, do I have to tell him? (According to my acquaintances, he'll take it lightly and not get angry and stuff, but the next time he has the opportunity to eat without kosher, he'll tell me, "Here it is at that place"). That the rabbi won't ask me what my friend thinks about God and the Torah is something I can't understand from him and get clear statements about opinions from him, it's just how he and his entire family do it.